As such a type of steering device, a tilt fixing device for a tilt type steering column has been proposed that includes, for example, a tilt bolt that is inserted from a tilt bracket to a tilt lever and whose screw portion at one end thereof is screwed with a nut and a pair of a fixed cam member and a movable cam member that are provided on a side of the tilt bolt opposite to the nut, whose respective facing cam protrusions are engaged with each other, and whose respective bosses on back surfaces thereof are each engaged with the tilt bracket and the tilt lever, in which a clamping force is generated between the tilt bolt and the nut by operation of the tilt lever to lock and unlock the steering column.
The cam protrusions of the fixed cam member and the movable cam member each include a flat cam surface and inclined cams continuing with a downward inclination in a circumferential direction from the flat cam surface. The movable cam member is rotated so that the mutual flat cam surfaces are abutted against and engaged with each other, whereby an axial force is applied to the tilt bolt to lock and unlock the steering column.
Herein, in such a tilt fixing device, when clamping of the clamp mechanism is released, the axial force in a clamping direction escapes and constituent components become in a free state. At that time, due to the own weight of the tilt lever and inertia of an operation force in a direction of the release, a stopper of the movable cam member forcefully hits against a stopper of the fixed cam member to make a metal hitting sound.
As a technique for eliminating such a hitting sound occurring in adjustment of a tilt position, there has been disclosed a technique that provides smooth sliding of a fixed cam member in adjustment of a tilt position and reduces a hitting sound occurring when a protruded portion of a fixed cam member is abutted against a groove end portion of a long groove for tilt-position adjustment at a tilt-position adjustment end by integrally forming the fixed cam member and a locking unit made of a synthetic resin (see Patent Literature 1).
However, although the steering device of Patent Literature 1 serves to reduce a sliding sound and a hitting sound occurring between the fixed cam member and the long groove for tilt-position adjustment, it does not reduce a hitting sound between a movable cam member and the fixed cam member forming a clamp mechanism.
On the other hand, in order to decelerate the releasing speed of a tilt lever, in Patent Literature 2, an elastic member is provided on bottom surfaces of cam protrusions of a clamp mechanism. The elastic member is provided to contact with cam protrusions of a mating cam and brake the cam when releasing the tilt lever.